MARTIN — DISCUSSION ON CAIU'INOMA. 



601 



results in an epithelioma ; thei'e occurs inen^ly a superficial growth of 

 epithelium, layer upot I.'yer, never tending to l)eco:ne malignant, 

 never forming metastases. 



Where chnmic inHanniiation exists there ensues frequently an 

 extensive downward growth of the epithelial structures, hut always 

 more or less regular in its dlstrihution. There are, however, occasions 

 where scar tissue can develop into an atypical growth of epithelium, 

 and this, it must be admitted, is difficult to explain. Here again, 

 however, chronic irritation alone will fail to give an explanation, else 

 the condition should be far more frecjuent than actually occurs. 



It would seem that irritation alone, then, cannot explain the forma- 

 tion of cancerous tumours, that to the more activity of epithelial cells 

 alone cannot be accredited the formation of cancers, and it would 

 seem that our only resource is to examine for some deeper cause, to 

 search for the original stimulus which brings to the cells the power 

 to proliferate. It has been shown how characteristic are new growths 

 as the result of parasitic invasion and how scarce are evidences «f 

 similar growths in diseases that are proven to be non-parasitic. 80 

 that placing together all our facts we feel that, for the pre.sent at 

 least, there still remains a hope that in the near future something 

 more may be discovered to account for the similarity of mai.j. it 

 processes to those in the infective diseases. 



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